If you think divorce is inevitable and she's spending on
marital home surely these improvements will help property gain a better price, assuming you'd have to sell and split proceeds i.e. if this is your sole property and you have no kids.
If you are sure marriage is not salvageable and you have grounds to file a petition you might as well start the process as these things can really drag on.
Clearly get some advice if you're unsure about process. I believe it is mandatory for couples to get
mediation before taking case to court - hopefully you can get this sorted amicably but in my experience if the horse has already bolted it's best to get closure and go all the way to
Decree Absolute as quickly as you can.
Best of luck